US10017839B2 - Method for leaching valuable metals contained in waste denitrification catalyst by using roasting and water leaching - Google Patents
Method for leaching valuable metals contained in waste denitrification catalyst by using roasting and water leaching Download PDFInfo
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- US10017839B2 US10017839B2 US14/425,129 US201314425129A US10017839B2 US 10017839 B2 US10017839 B2 US 10017839B2 US 201314425129 A US201314425129 A US 201314425129A US 10017839 B2 US10017839 B2 US 10017839B2
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B34/00—Obtaining refractory metals
- C22B34/20—Obtaining niobium, tantalum or vanadium
- C22B34/22—Obtaining vanadium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B34/00—Obtaining refractory metals
- C22B34/30—Obtaining chromium, molybdenum or tungsten
- C22B34/36—Obtaining tungsten
- C22B34/365—Obtaining tungsten from spent catalysts
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/005—Preliminary treatment of scrap
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
- C22B3/04—Extraction of metal compounds from ores or concentrates by wet processes by leaching
- C22B3/12—Extraction of metal compounds from ores or concentrates by wet processes by leaching in inorganic alkaline solutions
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
- C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
- C22B3/22—Treatment or purification of solutions, e.g. obtained by leaching by physical processes, e.g. by filtration, by magnetic means, or by thermal decomposition
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B34/00—Obtaining refractory metals
- C22B34/20—Obtaining niobium, tantalum or vanadium
- C22B34/22—Obtaining vanadium
- C22B34/225—Obtaining vanadium from spent catalysts
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B34/00—Obtaining refractory metals
- C22B34/30—Obtaining chromium, molybdenum or tungsten
- C22B34/36—Obtaining tungsten
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/009—General processes for recovering metals or metallic compounds from spent catalysts
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Y02P10/214—
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- Y02P10/23—
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- Y02P10/234—
Definitions
- the present invention relates to a method for leaching valuable metals from a waste denitrification catalyst, and, more particularly, to a method for leaching valuable metals such as vanadium (V) and tungsten (W) from a waste denitrification catalyst in an eco-friendly and economical manner.
- V vanadium
- W tungsten
- An exhaust apparatus in a power plant and the like contains a selective catalytic reduction (SCR) catalyst which effectively removes nitrogen oxide (NO x ).
- SCR selective catalytic reduction
- NO x nitrogen oxide
- Such a selective catalytic reduction catalyst is used for three to four years and recycled twice to three times. Thereafter, the catalyst is discarded in the form of a waste denitrification catalyst.
- a waste denitrification catalyst contains valuable metals, such as vanadium (V) and tungsten (W), in the form of oxides.
- V vanadium
- W tungsten
- vanadium oxide (V 2 O 5 ) is present in an amount of about 1% by weight (wt %) to about 3 wt %
- tungsten oxide WO 3 is present in an amount of about 7 wt % to about 10 wt %.
- Korean Patent Publication No. 10-2004-0067396 A discloses a method wherein a waste denitrification catalyst is treated to be used as a photocatalyst based on the fact that a large amount of titanium oxide is contained in the waste denitrification catalyst.
- valuable metals such as vanadium (V) and tungsten (W)
- a method for leaching valuable metals from a waste denitrification catalyst includes: (a) mixing a waste denitrification catalyst containing vanadium (V) and tungsten (W) in the form of oxides with an alkali metal compound to form a mixture; (b) roasting the mixture to produce a roasted product containing sodium vanadate (NaVO 3 ) and sodium tungstate (Na 2 WO 4 ); and (c) introducing the roasted product into water to water leach sodium vanadate and sodium tungstate in the form of a vanadate ion (VO 3 ⁇ ) and a tungstate ion (WO 4 2 ⁇ ).
- the alkali metal compound may include sodium carbonate (Na 2 CO 3 ) or sodium hydroxide (NaOH).
- the alkali metal compound is preferably mixed in an amount of 5 wt % to 40 wt % based on 100 wt % of the waste denitrification catalyst, more preferably in an amount of 15 wt % to 30 wt % based on 100 wt % of the waste denitrification catalyst.
- Step (b) may be performed at 800° C. to 900° C.
- the roasted product may be introduced in an amount of 10 wt % to 30 wt % based on 100 wt % of water.
- Step (c) may be performed at 40° C. to 60° C.
- the method may further include (d) filtering a leachate containing the vanadate ion and the tungstate ion.
- a method for leaching valuable metals from a waste denitrification catalyst includes: (a) mixing a waste denitrification catalyst containing valuable metals with an alkali metal compound to form a mixture; (b) roasting the mixture to produce a roasted product; and (c) water leaching the valuable metals from the roasted product.
- the method for leaching valuable metals from a waste denitrification catalyst according to the present invention can efficiently leach valuable metals, such as vanadium (V), tungsten (W), and the like, contained in a waste denitrification catalyst in an eco-friendly and economical manner by roasting at high temperature and water leaching.
- valuable metals such as vanadium (V), tungsten (W), and the like
- FIG. 2 is a graph depicting changes in leaching rate of vanadium as a function of the amount of an alkali metal compound.
- FIG. 3 is a graph depicting changes in leaching rate of tungsten as a function of the amount of an alkali metal compound.
- FIG. 4 is a graph depicting equilibrium pH of a leachate upon water leaching.
- FIG. 5 shows a result of SEM analysis on a waste denitrification catalyst
- FIG. 6 shows a result of SEM analysis on a roasted product.
- FIG. 6 shows a result of SEM analysis on a roasted product.
- FIG. 7 is a graph depicting changes in leaching rate of vanadium and tungsten as a function of roasting temperature.
- FIG. 8 is a graph depicting changes in leaching rate of vanadium and tungsten as a function of particle size of a waste denitrification catalyst.
- FIG. 1 is a schematic flowchart showing a method for leaching valuable metals contained in waste denitrification catalysts according to one embodiment of the present invention.
- the method for leaching valuable metals includes mixing a waste denitrification catalyst with an alkali metal compound (S 110 ), roasting (S 120 ), and water leaching (S 130 ).
- the waste denitrification catalyst containing valuable metals is mixed with the alkali metal compound to form a mixture. More specifically, the waste denitrification catalyst containing vanadium (V) and tungsten (W) in the form of an oxide (V 2 O 5 , WO 3 ) is mixed with the alkali metal compound to form a mixture.
- Vanadium (V) and tungsten (W) have very low solubility in water and are present in the form of vanadium oxide (V 2 O 5 ) and tungsten oxide (WO 3 ), which are difficult to water leach.
- vanadium and tungsten be in the form of an alkali metal salt, such as a sodium salt, having high solubility in water to facilitate water leaching.
- the waste denitrification catalyst is mixed with the alkali metal compound, whereby sodium vanadate (NaVO 3 ) and sodium tungstate (Na 2 WO 4 ) having relatively high solubility in water can be formed by roasting at high temperature.
- alkali metal compound sodium carbonate (Na 2 CO 3 ) or sodium hydroxide (NaOH) may be used in terms of reaction rate, although various alkali metal compounds may be used.
- roasting the mixture of the waste denitrification catalyst and the alkali metal compound is subject to roasting at high temperature, thereby producing a roasted product, more particularly, a roasted product containing sodium vanadate (NaVO 3 ) and sodium tungstate (Na 2 WO 4 ) having high solubility in water.
- Roasting may be performed at 800° C. to 900° C. If roasting is performed at a temperature of less than 800° C., there is a possibility of insufficient roasting. If roasting is performed at a temperature of higher than 900° C., this can reduce leaching rate of valuable metals without enhancing roasting, depending upon kind of the alkali metal compound.
- the method may further include ball milling the roasted product to reduce a particle size of the roasted product.
- a particle size of the roasted product According to experimental results, as the roasted product was reduced in particle size, i.e. average particle diameter, the roasted product was increased in surface area, which led to higher leaching rate.
- the roasted product is introduced into water to leach valuable metals from the roasted product. More specifically, the roasted product is introduced into water, thereby leaching sodium vanadate and sodium tungstate in the form of vanadate ions (VO 3 ⁇ ) and tungstate ions (WO 4 2 ⁇ ).
- Water leaching reactions of sodium vanadate and sodium tungstate may be represented as follows, respectively: NaVO 3 +H 2 O ⁇ Na + +VO 3 ⁇ +H 2 O Na 2 WO 4 +H 2 O ⁇ 2Na + +WO 4 2 ⁇ +H 2 O
- the roasted product may be introduced in an amount of 10 wt % to 30 wt % based on 100 wt % of water. If the amount of the roasted product is less than 10 wt %, leached valuable metals can be too small. On the contrary, if the amount of the roasted product is higher than 30 wt %, there is a possibility of deterioration in overall leaching efficiency of valuable metals due to inability to further enhance leaching.
- Water leaching may be performed at 40° C. to 60° C. If water leaching is performed at a temperature of less than 40° C., there is a possibility of reduction in water leaching rate, and if water leaching is performed at a temperature of higher than 60° C., there is a possibility of deterioration in stability of a leachate.
- the method may further include, after water leaching, filtering a leachate containing the vanadate ions and the tungstate ions to remove unnecessary impurities.
- a waste denitrification catalyst used in Example was obtained from Samcheon Thermal Power Generation Center (Korea) and was subjected to coarse crushing and fine crushing.
- tungsten and vanadium, as valuable metals to be recovered were present in an amount of about 7.7 wt % and about 1.2 wt %, respectively, in terms of oxide thereof; a main component was TiO 2 present in an amount of 70 wt % or more; and CaO, Al 2 O 3 , MgO, and the like, as binders, were present in a small amount.
- Example 2 in order to leach valuable metals from a waste denitrification catalyst, mixing a waste denitrification catalyst with an alkali metal compound, roasting at high temperature, and water leaching were performed, under varying conditions.
- roasting at high temperature amount of the alkali metal compound, roasting temperature, and particle size of waste catalyst particles were set as parameters.
- roasting at high temperature was performed using a muffle furnace (HM-1204, Hanmi High Tech Co., Ltd.), and water leaching after roasting at high temperature was performed using a leaching bath manufactured in house.
- HM-1204 Hanmi High Tech Co., Ltd.
- roasting was conducted while changing the amount of the alkali metal compound from 2.5 wt % to 40 wt % based on 100 wt % of the waste denitrification catalyst.
- Roasting was performed under conditions of a roasting temperature of 900° C., a waste catalyst particle size of 140 mesh, and a roasting time of 120 minutes. 20 wt % of a roasted product was introduced into 100 wt % of water, followed by water leaching at a leaching temperature of 50° C.
- FIG. 2 is a graph depicting changes in leaching rate of vanadium as a function of the amount of the alkali metal compound
- FIG. 3 is graph depicting changes in leaching rate of tungsten as a function of the amount of the alkali metal compound.
- FIG. 4 is a graph depicting equilibrium pH of a leachate upon water leaching.
- FIG. 5 shows a result of SEM analysis on the waste denitrification catalyst
- FIG. 6 shows a result of SEM analysis of the roasted product.
- FIGS. 5 and 6 it can be seen that a product after roasting at high temperature exhibits a crystalline form ( FIG. 6 ) which changes into a bar shape, unlike a crystalline form ( FIG. 5 ) of an original waste denitrification catalyst sample.
- roasting temperature on leaching rate was a roasting experiment was conducted while varying the roasting temperature from 800° C. to 900° C. Roasting was performed under conditions of an amount of the alkali metal compound of 20 wt % based on 100 wt % of the waste denitrification catalyst, a waste catalyst particle size of 140 mesh, and a roasting time of 120 minutes. 20 wt % of a roasted product was introduced into 100 wt % of water, followed by water leaching at a leaching temperature of 50° C.
- FIG. 7 is a graph depicting changes in leaching rate of vanadium and tungsten as a function of roasting temperature.
- leaching rate was higher than or equal to 50% at any roasting temperature within the range of 800° C. to 900° C.
- roasting was performed under conditions of an amount of the alkali metal compound of 20 wt % based on 100 wt % of the waste denitrification catalyst, a roasting temperature of 900° C., and a roasting time of 120 minutes. 20 wt % of a roasted product was introduced into 100 wt % of water, followed by water leaching at a leaching temperature of 50° C.
- FIG. 8 is a graph depicting changes in leaching rate of vanadium and tungsten as a function of particle size of the waste denitrification catalyst.
- Na 2 CO 3 exhibited better leaching properties than NaOH under the same conditions, and, in particular, exhibited properties advantageous to water leaching in terms of curing degree of a roasted product.
- Na 2 CO 3 is more advantageous to operation than NaOH, which is highly corrosive.
Abstract
Disclosed is a method for effectively leaching valuable metals such as vanadium and tungsten contained in a waste denitrification catalyst by using roasting and water leaching. According to the present invention, the method for leaching valuable metals contained in a waste denitrification catalyst comprises the steps of: (a) mixing a waste denitrification catalyst containing vanadium (V) and tungsten (W) in the form of an oxide with an alkali metal compound to form a mixture; (b) roasting the mixture to generate a roasting product comprising sodium vanadate (NaVO3) and sodium tungstate (Na2WO4); and (c) injecting the roasting product into water to water leach sodium vanadate and sodium tungstate in the form of a vanadate ion (VO3 −) and a tungstate ion (WO4 2−).
Description
The present invention relates to a method for leaching valuable metals from a waste denitrification catalyst, and, more particularly, to a method for leaching valuable metals such as vanadium (V) and tungsten (W) from a waste denitrification catalyst in an eco-friendly and economical manner.
An exhaust apparatus in a power plant and the like contains a selective catalytic reduction (SCR) catalyst which effectively removes nitrogen oxide (NOx). Typically, such a selective catalytic reduction catalyst is used for three to four years and recycled twice to three times. Thereafter, the catalyst is discarded in the form of a waste denitrification catalyst.
A waste denitrification catalyst contains valuable metals, such as vanadium (V) and tungsten (W), in the form of oxides. Generally, in the waste denitrification catalyst, vanadium oxide (V2O5) is present in an amount of about 1% by weight (wt %) to about 3 wt %, and tungsten oxide WO3 is present in an amount of about 7 wt % to about 10 wt %.
Thus, if a waste denitrification catalyst is discarded without additional use, this results in not only a burden of waste disposal costs but also loss of valuable natural resources.
However, until now, there have been few studies on recovery of valuable metals from a waste denitrification catalyst and thus such a waste denitrification catalyst has, traditionally, simply been abandoned. Therefore, there is a need for a method of recovering valuable metals from a waste denitrification catalyst.
Korean Patent Publication No. 10-2004-0067396 A (publication date: Jul. 30, 2004) discloses a method wherein a waste denitrification catalyst is treated to be used as a photocatalyst based on the fact that a large amount of titanium oxide is contained in the waste denitrification catalyst.
It is an aspect of the present invention to provide a method for leaching valuable metals, such as vanadium (V) and tungsten (W), from a waste denitrification catalyst in an efficient manner.
In accordance with one embodiment of the present invention, a method for leaching valuable metals from a waste denitrification catalyst includes: (a) mixing a waste denitrification catalyst containing vanadium (V) and tungsten (W) in the form of oxides with an alkali metal compound to form a mixture; (b) roasting the mixture to produce a roasted product containing sodium vanadate (NaVO3) and sodium tungstate (Na2WO4); and (c) introducing the roasted product into water to water leach sodium vanadate and sodium tungstate in the form of a vanadate ion (VO3 −) and a tungstate ion (WO4 2−).
The alkali metal compound may include sodium carbonate (Na2CO3) or sodium hydroxide (NaOH).
In step (a), the alkali metal compound is preferably mixed in an amount of 5 wt % to 40 wt % based on 100 wt % of the waste denitrification catalyst, more preferably in an amount of 15 wt % to 30 wt % based on 100 wt % of the waste denitrification catalyst.
Step (b) may be performed at 800° C. to 900° C.
The method may further include, after step (b), ball milling the roasted product to reduce a particle size of the roasted product.
In step (c), the roasted product may be introduced in an amount of 10 wt % to 30 wt % based on 100 wt % of water.
Step (c) may be performed at 40° C. to 60° C.
The method may further include (d) filtering a leachate containing the vanadate ion and the tungstate ion.
In accordance with another embodiment of the present invention, a method for leaching valuable metals from a waste denitrification catalyst includes: (a) mixing a waste denitrification catalyst containing valuable metals with an alkali metal compound to form a mixture; (b) roasting the mixture to produce a roasted product; and (c) water leaching the valuable metals from the roasted product.
The method for leaching valuable metals from a waste denitrification catalyst according to the present invention can efficiently leach valuable metals, such as vanadium (V), tungsten (W), and the like, contained in a waste denitrification catalyst in an eco-friendly and economical manner by roasting at high temperature and water leaching.
The above and other aspects, features, and advantages of the present invention will become apparent from the detailed description of the following embodiments in conjunction with the accompanying drawings.
It should be understood that the present invention is not limited to the following embodiments and may be embodied in different ways, and that the embodiments are provided for complete disclosure and thorough understanding of the present invention by those skilled in the art. The scope of the present invention is defined only by the claims.
Hereinafter, a method for leaching valuable metals from a waste denitrification catalyst using roasting and water leaching according to the present invention will be described in detail.
Referring to FIG. 1 , the method for leaching valuable metals includes mixing a waste denitrification catalyst with an alkali metal compound (S110), roasting (S120), and water leaching (S130).
First, in mixing the waste denitrification catalyst with the alkali metal compound (S110), the waste denitrification catalyst containing valuable metals is mixed with the alkali metal compound to form a mixture. More specifically, the waste denitrification catalyst containing vanadium (V) and tungsten (W) in the form of an oxide (V2O5, WO3) is mixed with the alkali metal compound to form a mixture.
Vanadium (V) and tungsten (W) have very low solubility in water and are present in the form of vanadium oxide (V2O5) and tungsten oxide (WO3), which are difficult to water leach. Thus, it is desirable that vanadium and tungsten be in the form of an alkali metal salt, such as a sodium salt, having high solubility in water to facilitate water leaching.
For this reason, in this operation, the waste denitrification catalyst is mixed with the alkali metal compound, whereby sodium vanadate (NaVO3) and sodium tungstate (Na2WO4) having relatively high solubility in water can be formed by roasting at high temperature.
Here, as the alkali metal compound, sodium carbonate (Na2CO3) or sodium hydroxide (NaOH) may be used in terms of reaction rate, although various alkali metal compounds may be used.
In addition, experimental results show that mixing the alkali metal compound in an amount of 5 wt % to 40 wt % based on 100 wt % of the waste denitrification catalyst is advantageous in terms of leaching rate, and mixing the alkali metal compound in an amount of 15 wt % to 30 wt % based on 100 wt % of the waste denitrification catalyst is more advantageous in terms of securing high leaching rate of both vanadium and tungsten.
Next, in roasting (S120), the mixture of the waste denitrification catalyst and the alkali metal compound is subject to roasting at high temperature, thereby producing a roasted product, more particularly, a roasted product containing sodium vanadate (NaVO3) and sodium tungstate (Na2WO4) having high solubility in water.
In roasting using sodium carbonate and sodium hydroxide, vanadium oxide and tungsten oxide react as follows:
V2O5(s)+Na2CO3(s)=2NaVO3(s)+CO2(g) (1)
WO3(s)+Na2CO3(s)=Na2WO4(s)+CO2(g) (2)
V2O5(s)+2NaOH=2NaVO3+H2O(g) (3)
WO3(s)+2NaOH=Na2WO4+H2O(g) (4)
V2O5(s)+Na2CO3(s)=2NaVO3(s)+CO2(g) (1)
WO3(s)+Na2CO3(s)=Na2WO4(s)+CO2(g) (2)
V2O5(s)+2NaOH=2NaVO3+H2O(g) (3)
WO3(s)+2NaOH=Na2WO4+H2O(g) (4)
Roasting may be performed at 800° C. to 900° C. If roasting is performed at a temperature of less than 800° C., there is a possibility of insufficient roasting. If roasting is performed at a temperature of higher than 900° C., this can reduce leaching rate of valuable metals without enhancing roasting, depending upon kind of the alkali metal compound.
The method may further include ball milling the roasted product to reduce a particle size of the roasted product. According to experimental results, as the roasted product was reduced in particle size, i.e. average particle diameter, the roasted product was increased in surface area, which led to higher leaching rate.
Next, the roasted product is introduced into water to leach valuable metals from the roasted product. More specifically, the roasted product is introduced into water, thereby leaching sodium vanadate and sodium tungstate in the form of vanadate ions (VO3 −) and tungstate ions (WO4 2−).
Water leaching reactions of sodium vanadate and sodium tungstate may be represented as follows, respectively:
NaVO3+H2O→Na++VO3 −+H2O
Na2WO4+H2O→2Na++WO4 2−+H2O
NaVO3+H2O→Na++VO3 −+H2O
Na2WO4+H2O→2Na++WO4 2−+H2O
In water leaching, the roasted product may be introduced in an amount of 10 wt % to 30 wt % based on 100 wt % of water. If the amount of the roasted product is less than 10 wt %, leached valuable metals can be too small. On the contrary, if the amount of the roasted product is higher than 30 wt %, there is a possibility of deterioration in overall leaching efficiency of valuable metals due to inability to further enhance leaching.
Water leaching may be performed at 40° C. to 60° C. If water leaching is performed at a temperature of less than 40° C., there is a possibility of reduction in water leaching rate, and if water leaching is performed at a temperature of higher than 60° C., there is a possibility of deterioration in stability of a leachate.
The method may further include, after water leaching, filtering a leachate containing the vanadate ions and the tungstate ions to remove unnecessary impurities.
Hereinafter, the present invention will be described in more detail with reference to a preferred example. It should be understood that these examples are not to be construed in any way as limiting the present invention.
A description of details apparent to those skilled in the art will be omitted.
A waste denitrification catalyst used in Example was obtained from Samcheon Thermal Power Generation Center (Korea) and was subjected to coarse crushing and fine crushing.
Thereafter, component analysis was performed on the waste denitrification catalyst, thereby obtaining results as listed in Table 1.
TABLE 1 | |||||||||
Comp. | Al2O3 | WO3 | V2O5 | CaO | MgO | SiO2 | WO3 | Fe2O3 | TiO2 |
Wt % | 5.57 | 7.73 | 1.23 | 2.45 | 0.55 | 9.80 | 0.10 | 0.77 | Remainder |
As shown in Table 1, tungsten and vanadium, as valuable metals to be recovered, were present in an amount of about 7.7 wt % and about 1.2 wt %, respectively, in terms of oxide thereof; a main component was TiO2 present in an amount of 70 wt % or more; and CaO, Al2O3, MgO, and the like, as binders, were present in a small amount.
In Example, in order to leach valuable metals from a waste denitrification catalyst, mixing a waste denitrification catalyst with an alkali metal compound, roasting at high temperature, and water leaching were performed, under varying conditions.
Here, in roasting at high temperature, amount of the alkali metal compound, roasting temperature, and particle size of waste catalyst particles were set as parameters.
Roasting at high temperature was performed using a muffle furnace (HM-1204, Hanmi High Tech Co., Ltd.), and water leaching after roasting at high temperature was performed using a leaching bath manufactured in house.
After soda roasting, valuable metals in a leachate were analyzed using an ICP-AES (iCAP6300 DUO, ThermoElectron Corp.), thereby calculating leaching rate.
In order to investigate roasting properties of the waste denitrification catalyst according to changes in amount of the alkali metal compound (NaOH, NaCO3), a roasting experiment was conducted while changing the amount of the alkali metal compound from 2.5 wt % to 40 wt % based on 100 wt % of the waste denitrification catalyst. Roasting was performed under conditions of a roasting temperature of 900° C., a waste catalyst particle size of 140 mesh, and a roasting time of 120 minutes. 20 wt % of a roasted product was introduced into 100 wt % of water, followed by water leaching at a leaching temperature of 50° C.
As shown in FIGS. 2 and 3 , experimental results given varying amounts of the alkali metal compound show that leaching rates of vanadium and tungsten increase with increasing amount of the alkali metal compound. However, when NaOH was added in an amount of 40 wt % based on 100 wt % of the waste denitrification catalyst, the roasted product was excessively hardened, such that normal water leaching was impossible. This is because, such a muffle type roasting furnace cannot benefit from a stirring effect. Thus, when a rotary kiln furnace, which allows stirring, is used, it is possible to increase the amount of NaOH.
In addition, referring to FIGS. 2 and 3 , it can be seen that, when the alkali metal compound is added in an amount of about 10 wt % or more based on 100 wt % of the waste denitrification catalyst, a substantially good leaching rate is obtained. Particularly, as shown in FIGS. 2 and 3 , leaching rates of vanadium and tungsten are both about 50% or higher when the alkali metal compound is present in an amount of 15 wt % to 30 wt % based on 100 wt % of the waste denitrification catalyst. Within this range, the most preferable results can be obtained.
Referring to FIG. 4 , it can be seen that pH increases with increasing amount of added alkali. However, this result is not proportional to the leaching rates in FIGS. 2 and 3 . It is understood that increase in amount of the alkali metal compound causes the roasted product to crystallize, thereby adversely affecting water leaching while allowing increase in leaching agents.
Referring to FIGS. 5 and 6 , it can be seen that a product after roasting at high temperature exhibits a crystalline form (FIG. 6 ) which changes into a bar shape, unlike a crystalline form (FIG. 5 ) of an original waste denitrification catalyst sample.
This can be indirect evidence accounting for a phenomenon that an excess of the alkali metal compound causes reduction in leaching rate.
In order to identify effect of roasting temperature on leaching rate, a roasting experiment was conducted while varying the roasting temperature from 800° C. to 900° C. Roasting was performed under conditions of an amount of the alkali metal compound of 20 wt % based on 100 wt % of the waste denitrification catalyst, a waste catalyst particle size of 140 mesh, and a roasting time of 120 minutes. 20 wt % of a roasted product was introduced into 100 wt % of water, followed by water leaching at a leaching temperature of 50° C.
Experimental results show that, when Na2CO3 was used as the alkali metal compound, effect of roasting temperature was insignificant. However, when NaOH was used as the alkali metal compound, leaching rate had a maximum value at 850° C. After the experiment, through comparison of curing degree of roasted products, it was confirmed that products obtained by roasting a mixture containing NaOH were harder. Thus, it is understood that such properties of the roasted products affects leaching efficiency.
However, when the alkali metal compound was added in an amount of 20 wt %, leaching rate was higher than or equal to 50% at any roasting temperature within the range of 800° C. to 900° C.
In order to identify effect of particle size of a waste denitrification catalyst on leaching rate, a roasting experiment was conducted while varying particle size of the waste denitrification catalyst. Here, roasting was performed under conditions of an amount of the alkali metal compound of 20 wt % based on 100 wt % of the waste denitrification catalyst, a roasting temperature of 900° C., and a roasting time of 120 minutes. 20 wt % of a roasted product was introduced into 100 wt % of water, followed by water leaching at a leaching temperature of 50° C.
Referring to FIG. 8 , it was confirmed that effect of particle size on leaching rate was insignificant.
On the other hand, referring to FIGS. 2 to 8 , as the alkali metal compound, Na2CO3 exhibited better leaching properties than NaOH under the same conditions, and, in particular, exhibited properties advantageous to water leaching in terms of curing degree of a roasted product.
In addition, in a continuous roasting process using a rotary kiln furnace, which allows stirring, Na2CO3 is more advantageous to operation than NaOH, which is highly corrosive.
Although some embodiments have been described above with reference to the accompanying drawings, it should be understood that the present invention is not limited to these embodiments and may be embodied in different ways, and that various modifications, variations, and alterations can be made without departing from the spirit and scope of the invention. Therefore, it should be understood that the above embodiments are provided for illustration only and do not limit the scope of the present invention.
Claims (14)
1. A method for leaching valuable metals from a waste denitrification catalyst, comprising:
(a) mixing a waste denitrification catalyst containing vanadium (V) and tungsten (W) in the form of oxides with an alkali metal compound in an amount of 5 wt % to 40 wt % based on 100 wt % of the waste denitrification catalyst to form a mixture;
(b) roasting the mixture to produce a roasted product containing sodium vanadate (NaVO3) and sodium tungstate (Na2WO4); and
(c) introducing the roasted product into water to water leach sodium vanadate and sodium tungstate in the form of vanadate ions (VO3 −) and tungstate ions (WO4 2−).
2. The method according to claim 1 , wherein the alkali metal compound is sodium carbonate (Na2CO3) or sodium hydroxide (NaOH).
3. The method according to claim 1 , wherein step (b) is performed at 800° C. to 900° C.
4. The method according to claim 1 , further comprising, after step (b), ball milling the roasted product to reduce a particle size of the roasted product.
5. The method according to claim 1 , wherein, in step (c), the roasted product is introduced in an amount of 10 wt % to 30 wt % based on 100 wt % of water.
6. The method according to claim 1 , wherein step (c) is performed at 40° C. to 60° C.
7. The method according to claim 1 , further comprising, after step (c), filtering a leachate containing the vanadate ions and the tungstate ions.
8. A method for leaching valuable metals from a waste denitrification catalyst, comprising:
(a) mixing a waste denitrification catalyst containing valuable metals with an alkali metal compound in an amount of 5 wt % to 40 wt % based on 100 wt % of the waste denitrification catalyst to form a mixture;
(b) roasting the mixture to produce a roasted product; and
(c) introducing the roasted product into water to water leach the valuable metals from the roasted product.
9. The method according to claim 8 , wherein the alkali metal compound is sodium carbonate (Na2CO3) or sodium hydroxide (NaOH).
10. The method according to claim 8 , wherein step (b) is performed at 800° C. to 900° C.
11. The method according to claim 8 , further comprising, after step (b), ball milling the roasted product to reduce a particle size of the roasted product.
12. The method according to claim 8 , wherein, in step (c), the roasted product is introduced in an amount of 10 wt % to 30 wt % based on 100 wt % of water.
13. The method according to claim 8 , wherein step (c) is performed at 40° C. to 60° C.
14. The method according to claim 8 , further comprising, after step (c), filtering a leachate containing vanadate ions and tungstate ions.
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KR20120099496A KR101281579B1 (en) | 2012-09-07 | 2012-09-07 | Method of leaching valuable metal in spent catalyst of denitrification using roasting water leaching |
KR10-2012-0099496 | 2012-09-07 | ||
PCT/KR2013/000421 WO2014038762A1 (en) | 2012-09-07 | 2013-01-18 | Method for leaching valuable metals contained in waste denitrification catalyst by using roasting and water leaching |
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KR101466928B1 (en) * | 2014-03-05 | 2014-12-03 | 한국지질자원연구원 | Leaching method of valuable metal in spent catalyst of denitrification using high pressured leaching process |
CN105112691A (en) * | 2015-10-10 | 2015-12-02 | 江西理工大学 | Method for extracting tungsten from tungsten minerals through alkaline decomposition |
KR101813233B1 (en) * | 2017-07-27 | 2017-12-28 | 한국지질자원연구원 | Selective recovery method for valuable metal from spent SCR catalyst using alkali fusion |
CN107502746A (en) * | 2017-08-22 | 2017-12-22 | 河钢股份有限公司承德分公司 | A kind of method for efficiently leaching vanadium tungsten in denitrating catalyst |
CN107720826A (en) * | 2017-09-14 | 2018-02-23 | 湖南力天高新材料股份有限公司 | A kind of method that sodium tungstate is extracted from tungsten waste |
KR101996425B1 (en) * | 2017-12-20 | 2019-07-05 | 오영복 | Method for recovering valuable metals from denitrification waste catalysts |
KR101957705B1 (en) * | 2018-10-24 | 2019-03-13 | 한국지질자원연구원 | Manufacturing method of titania from scr catalyst |
CN109897962B (en) * | 2019-03-14 | 2020-11-17 | 厦门钨业股份有限公司 | Method and device for recovering tungsten in tungsten-containing waste by adopting oxidation smelting method |
CN110468290B (en) * | 2019-08-06 | 2021-10-22 | 湖南懋天世纪新材料有限公司 | Application and method of sodium polyacrylate in treatment of waste tungsten material |
CN111778398A (en) * | 2019-10-22 | 2020-10-16 | 广东省资源综合利用研究所 | Method for extracting vanadium and tungsten from waste SCR denitration catalyst |
CN113387387A (en) * | 2021-08-03 | 2021-09-14 | 崇义章源钨业股份有限公司 | Method for preparing sodium tungstate solution by utilizing tungsten-containing waste in short process |
KR102445476B1 (en) | 2021-09-15 | 2022-09-21 | 주식회사 한내포티 | Method of extracting valuable metals containing denitrification waste catalyst using an alkali sintered body |
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